A tightly-sealing, non-corrosive miniature valve that can be baked and requires power only during on/off switching has many applications, especially in the semiconductor manufacturing industry. A tight seal (10e-10 SCCM) requires a large force. Ability to tolerate bake-out, corrosion resistance, and cleanliness (freedom from organic and hydrocarbon contaminants) limits suitable materials to stainless steel and similar metals. Large force, small volume, and light weight actuation are feasible using electrically- powered shape-memory alloy (SMA) devices. Incorporating a latching mechanism, so that power is required only during on/off switching, compensates for the large power requirement of SMA actuators. The proposed valve consists of a welded extensible tube containing a poppet and matching orifice. When closed, the poppet and orifice are pressed together by a bistable spring. The bistable spring latch mechanism is moved from closed to open position by a shape-memory actuator that elongates the extensible tube. A second SMA actuator reverses the latch from the open to the closed position. In Phase I, an all-metal poppet/orifice combination will be developed to give low leak rates, forceful SMA actuators will be designed and built, a suitable latching device will be designed, and proof-of-concept latching valves will be fabricated.
Potential Commercial Applications:Tightly-sealing, non-corrosive miniature valves that can be baked have significant market potential as shut-off valves in the semiconductor manufacturing industry. The planned device can be scaled to larger (or smaller) size, can control liquids as well as gasses, and is safer to use around hazardous materials such as fuels because the electrical load is purely resistive rather than inductive. Commercial applications include aerospace and transportation.
